The statements in this section merely provide background information related to the present disclosure and may not constitute the prior art.
Moving Picture Experts Group (MPEG) and Video Coding Experts Group (VCEG) have developed an improved and excellent video compression technology over existing MPEG-4 Part 2 and H.263 standards. The new standard is called H.264/AVC (Advanced Video Coding) and was released simultaneously as MPEG-4 Part 10 AVC and ITU-T Recommendation H.264.
In the image compression techniques such as H.264/AVC, various prediction techniques are employed including an inter prediction and an intra prediction to obtain effective image compressions. The above described intra prediction may be an intra_4×4 prediction, intra_16×16 prediction, intra_8×8 prediction and the like, where the respective intra predictions include a plurality of prediction modes.
The image compression techniques such as H.264/AVC select an optimal prediction mode out of a plurality of prediction modes and performs a prediction. Therefore, what prediction mode is to select for the optimal prediction mode and to perform the prediction determine the compression efficiency, and in order to select the optimal prediction mode, a prediction of the block is performed with respect to every prediction mode and then a cost is calculated using a predetermined cost function to eventually take the prediction mode with the lowest encoding cost.
Therefore, in order to determine the optimal prediction mode whether it is intra_4×4 prediction or intra_16×16 prediction, the cost should be calculated after trying every prediction mode. This makes an encoding process complex and lowers the compression efficiency.
Additionally, to correctly decode the image, information on the selected optimal prediction mode should also be encoded. In response to recent incremental requirements for higher resolution images, the number of blocks to be encoded has been increased resulting in greater quantity of bits required to encode the information on the optimal prediction mode with respect to each block, which degrades the compression efficiency.